2-Azetidinone derivatives are important as reactive compounds for forming the subsituent at the 13-position of an anticancer compound having the following structure.

As such a reactive compound, use is made of, for example, a compound (1) having the following structure (TIPS: triisopropylsilyl group, Boc: tertiary butoxycarbonyl group (hereinafter “tertiary” will be abbreviated as “t-”, i.e., “t-butoxycarbonyl group”)

This compound (1) is obtained by subjecting a racemic compound (2) (PMP: paramethoxyphenyl group (4-methoxyphenyl group), Ac: acetyl group, the acetoxy group at the 3-position and the 3-fluoro-2-pyridyl group at the 4-position being in the cis-configuration):
to deprotection of Ac at the 3-position, conversion into TIPS, recrystallization, elimination of PMP at the 1-position, and separation by column chromatography (which will be sometimes abbreviated as column hereinafter) to give: a compound (3):
followed by separation with the use of an optical resolution column and attachment of a protective group.
The process for obtaining the compound (1) from the racemic compound (2) suffers from a problem that troublesome procedures (epimerization, replacement of the solvent for recrystallization, isolation by the column, etc.) are needed and yet only a low yield can be achieved. To obtain the compound (1), there arises an additional problem that the compound (3) should be separated by using an optical resolution column in the step prior to the final step, which results in an increase in the cost in case of mass production.
The present invention aims at providing a production process whereby an optically active 2-azetidinone derivative can be easily produced in a large amount at a low cost.